Background
Total mesorectal excision (TME) is a common procedure used in the treatment of colorectal cancer in which a significant length of the bowel around the tumor is removed. TME addresses earlier treatment concerns regarding adequate local control of rectal cancer when an anterior resection is performed.
The term TME strictly applies in the performance of a low anterior resection for tumors of the middle and the lower rectum, wherein it is essential to remove the rectum along with the mesorectum up to the level of the levators.
The principles of TME (sharp mesorectal excision) are also applied during an abdominoperineal excision of the rectum and for tumors of the upper rectum, though these are considered distinct from standard TME. In an abdominoperineal excision of the rectum where the tumor exists below the level of the levators, the lateral margins of the tumor are inferior to the mesorectum, and the benefits of TME do not apply.
Anterior resections involving the upper rectum may be completed with mobilization of the rectum to beyond 5 cm of the lower margin of the tumor, and which is often above the level of the levator and is sometimes referred to as partial mesorectal excision.
The treatment of rectal cancers is multimodal, with adjuvant radiotherapy and chemotherapy having benefits in some settings. In addition, accurate preoperative staging is dependent on good radiologic support. It is therefore necessary to subject all rectal cancers to multidepartment conference and to design individualized treatment plans based on a well-defined protocol. This serves the dual purposes of maintaining a consistent evidence-based approach and creating a dataset for prospective analysis and feedback.
Indications
TME is indicated as a part of low anterior resection for patients with adenocarcinoma of the middle and lower rectum. It is now considered the gold standard for tumors of the middle and lower rectum. [1]
Outcomes
The circumferential resection margin positivity rate is about 5% or less for low anterior resections with TME, whereas it is between 10% and 25% for abdominoperineal excision of the rectum. There is, understandably, a higher local recurrence rate following abdominoperineal excision of the rectum. The 5-year survival and disease-free survival rates are significantly lower with TME.
Evidence suggests that a circumferential resection margin of 1 mm or less adversely affects cancer-specific survival, local recurrence, and distant metastasis. [2]
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Total mesorectal excision: Exploration and setup.
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Total mesorectal excision: Mobilization and division of the colon.
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Total mesorectal excision: Mobilization of the rectum and division.
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Total mesorectal excision: Reconstruction.
